首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ab Initio Study of Hydrogen Bonding and Proton Transfer in 3:1 FH:NH_3 and FH:Collidine Complexes: Structures and One-and Two-Bond Coupling Constants across Hydrogen Bonds
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Ab Initio Study of Hydrogen Bonding and Proton Transfer in 3:1 FH:NH_3 and FH:Collidine Complexes: Structures and One-and Two-Bond Coupling Constants across Hydrogen Bonds

机译:从头开始研究3:1 FH:NH_3和FH:Collidine配合物中的氢键和质子转移:氢键的结构以及一键和二键耦合常数

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Ab initio EOM-CCSD calculations have been performed on 3:1 FH:NH_3 complexes at their own optimized MP2/6-31+G(d,p)geometries and at the optimized geometries in the hydrogen-bonding regions of corresponding 3:1 FHxollidine complexes.The isolated gas-phase equilibrium 3:1 FH:NH_3 complex has an open structure with a proton-shared F_a-H_a-N hydrogen bond,while the isolated equilibrium 3:1 FHxollidine complex has a perpendicular structure with an F_a-H_a-N hydrogen bond that is on the ion-pair side of proton-shared.The F_a-N coupling constant(~(2h)J_(F_a-N))for the equilibrium 3:1 FH:NH_3 complex is large and negative,consistent with a proton-shared F_a-H_a-N hydrogen bond;~(2h)J_(F_b-F_a))is positive,reflecting a short F_b-F_a distance and partial proton transfer from F_b to F_a across the F_b-H_b-F_a hydrogen bond.In contrast,~(2h)J_(F_a-N))has a smaller absolute value and ~(2h)J_(F_b-F_a))is greater for the 3:1 FH:NH_3 complex at the equilibrium 3:1 FHxollidine geometry,consistent with the structural characteristics of the F_a-H_a-N and F_b-H_b-F_a hydrogen bonds.Coupling constants computed at proton-transferred 3:1 FHxollidine perpendicular geometries are consistent with experimental coupling constants for the 3:1 FHxollidine complex in solution and indicate that the role of the solvent is to promote further proton transfer from F_a to N across the F_a-H_a-N hydrogen bond,and from F_b to F_a across the two equivalent Fb-H_b-F_a hydrogen bonds.The best correlations between experimental and computed coupling constants are found for complexes with perpendicular proton-transferred structures,one having the optimized geometry of a 3:1 FHxollidine complex at an F_a-H_a distance of 1.80 A,and the other at the optimized 3:1 FHxollidine geometry with distances derived from the experimental coupling constants.These calculations provide support for the proposed perpendicular structure of the 3:1 FHxollidine complex as the structure which exists in solution.
机译:从头开始进行EOM-CCSD计算是针对3:1 FH:NH_3配合物,以其自身优化的MP2 / 6-31 + G(d,p)几何结构以及相应3:1的氢键区域中的优化几何结构进行的FHxollidine络合物。孤立的气相平衡3:1 FH:NH_3络合物具有带质子共享的F_a-H_a-N氢键的开放结构,而孤立的平衡的3:1 FHxollidine络合物具有F_a-的垂直结构。 H_a-N氢键位于质子共享的离子对侧。平衡的3:1 FH:NH_3络合物的F_a-N耦合常数(〜(2h)J_(F_a-N))大而为负,与质子共享的F_a-H_a-N氢键一致;〜(2h)J_(F_b-F_a))为正,反映了较短的F_b-F_a距离和质子从F_b到F_a跨F_b-H_b-的部分转移。 F_a氢键。相反,在平衡3处3:1 FH:NH_3络合物的〜(2h)J_(F_a-N))绝对值较小,〜(2h)J_(F_b-F_a))较大。 :1 FHxollidine几何形状,与F_a-H_a-N和F_b-H_b-F_a氢键的结构特征。在质子转移的3:1 FHxollidine垂直几何结构上计算的耦合常数与溶液中3:1 FHxollidine络合物的实验耦合常数一致,表明溶剂的作用是促进质子通过F_a-H_a-N氢键从F_a进一步转移到N,以及通过两个等效Fb-H_b-F_a氢键从F_b转移到F_a。实验耦合和计算耦合之间的最佳相关性对于具有垂直质子转移结构的复合物,发现常数,一个常数在F_a-H_a距离为1.80 A时具有优化的3:1 FHxollidine配合物的几何形状,另一个在优化的3:1 FHxollidine几何中具有从这些计算为所提出的3:1 FHxollidine复合物的垂直结构提供了支持,因为该结构存在于溶液中。

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